Cod sursa(job #2697717)

Utilizator FrostfireMagirescu Tudor Frostfire Data 19 ianuarie 2021 13:43:22
Problema Flux maxim Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.42 kb
#include <iostream>
#include <fstream>
#include <queue>
#define f first
#define s second
#define NMAX 1000
#define inf 2000000000

using namespace std;

ifstream fin("maxflow.in");
ofstream fout("maxflow.out");

int n, m, cost[NMAX+10][NMAX+10], p[NMAX+10], ans;
vector <int> nod[NMAX+10];
queue <int> Q;

int addFlow()
{	for(int i=1; i<=n; i++)
		p[i] = 0;
	p[1] = 1;
	while(!Q.empty())
		Q.pop();
	Q.push(1);

	while(!Q.empty())
		{	int a = Q.front();
			Q.pop();
			for(int i=0; i<nod[a].size(); i++)
				if(!p[nod[a][i]] && cost[a][nod[a][i]])
					{	p[nod[a][i]] = a;
						Q.push(nod[a][i]);
					}
		}
	return p[n];
}

int main()
{	
	fin >> n >> m;
	for(int i=1; i<=m; i++)
		{	int nod1, nod2, c;
			fin >> nod1 >> nod2 >> c;
			nod[nod1].push_back(nod2);
			nod[nod2].push_back(nod1);
			cost[nod1][nod2] += c;
		}
	while(addFlow())
		{	for(int i=1; i<n; i++)
				{	if(p[i] && cost[i][n])
						{	int newFlow = cost[i][n], curr = i;
							while(curr != 1)
								{	newFlow = min(newFlow, cost[p[curr]][curr]);
									curr = p[curr];
								}
							if(!newFlow) continue;
							cost[i][n] -= newFlow;
							cost[n][i] += newFlow;
							curr = i;
							while(curr != 1)
								{	cost[p[curr]][curr] -= newFlow;
									cost[curr][p[curr]] += newFlow;
									curr = p[curr];
								}
							ans += newFlow;
						}
				}
		}
	fout << ans << '\n';
	return 0;
}